The present disclosure relates to an image forming apparatus, a toner case installed in the image forming apparatus and a drive transmission mechanism installed in the image forming apparatus.
An electrographic image forming apparatus carries out the development process by supplying a toner (a developer) from a development device to an electrostatic latent image formed on the surface of a photosensitive drum or the like. The toner used in such development process is supplied from a toner case, such as a toner container or an intermediate hopper, to the development device. The above-mentioned toner case includes a case main body having a discharge port discharging the toner, a rotating member (e.g. an agitating paddle and a conveying screw) rotatably installed in the case main body and a following coupling connected to the rotating member. The rotating member is rotated by linking the above-mentioned following coupling to a drive coupling connected to a drive source, such as a motor.
For example, there is a configuration linking the drive coupling including a triangle-formed hole and following coupling including a triangle pole-formed protrusion. Alternatively, there is another configuration that the drive coupling and following coupling are formed in twisted-shapes. Moreover, there is a further configuration that the drive coupling and following coupling are formed to have tapered faces.
However, in the configuration linking the drive coupling including the triangle-formed hole and following coupling including the triangle pole-formed protrusion, in a case where a drive torque of the following coupling is large, there is a possibility that the linkage of the drive coupling and following coupling is accidentally released. As the case where the drive torque of the following coupling is large, for example, there are a case where a residual quantity of the toner in the toner case is large and a case where the toner in the toner case is solidified.
On the other hand, in the other configuration having the twisted-formed drive coupling and following coupling or the further configuration having the drive coupling and following coupling provided with the tapered faces, it is to some extent possible to prevent the linkage of the drive coupling and following coupling from being accidentally released. However, if the above-mentioned configurations are applied, shapes of the couplings are complicated, and accordingly, shapes of molds molding the couplings are also complicated. Therefore, in a case where it is desired to provide incompatibility of the couplings or other cases, it is difficult to mold the couplings in various shapes with maintaining the simple mold design.